Synthesis, characterization and luminescence properties of rare earth complexes with a new biphenylamide

A new amide-based ligand derived from biphenyl, N,N-dibenzyl-2-{2′-[(dibenzylcarbamoyl)-methoxy]-biphenyl-2-yloxy}-acetamide (L), and its complexes of rare earth picrates were synthesized. The complexes were characterized by elemental analysis, IR, 1H NMR, UV–Vis spectra and conductivity measurements. Under the excitation, the europium(III) complex exhibited characteristic emissions of europium. The luminescence properties of the europium(III) complex in solid state and in CHCl3, acetone, acetonitrile and DMF were investigated. The lifetime of the 5D0 level of the Eu3+ ion in the complex is 0.68 ms. The quantum yield Φ of the europium picrate complex was found to be 2.54×10−3 with quinine sulfate as reference. The lowest triplet state energy level of the ligand indicates that the triplet state energy level of the ligand matches better to the resonance level of Eu(III) than Tb(III) ion.